2D real-time phased array ultrasound has become a dominant medical imaging modality due to low costs, high efficacy and the absence of ionizing radiation. The total worldwide market for diagnostic ultrasound is $2 billion annually. Real-time phased array volumetric scanning systems (often called "4D Ultrasound Systems") promise an array of enhanced diagnostic capabilities, and will therefore replace 2D phased array ultrasound as the dominant ultrasound modality. 3D Ultrasound, Inc. owns the patent (Figure 1) for the only known effective mechanism for implementing 3D real-time ultrasound images, i.e., receive mode parallel processing. 3D Ultrasound, Inc. will develop a commercial fully featured scalable real time phased array volumetric scanner. The basis for this machine will be the real time phased array volumetric scanner at Duke University (the only known real time volumetric scanner in the world). Phase 1 of this research is directed toward the design, construction, and testing of a unique phased array receiver system based upon a custom VLSI mixed signal delay line chip. The verification of adequate performance of this system in terms of signal to noise, dynamic range, linearity, signal delay, power consumption, size and cost is essential prior to the design and construction of the complete real time volumetric imaging system.